Heat dissipation apparatus and manufacturing method thereof

ABSTRACT

A heat dissipation apparatus. The heat-dissipation apparatus comprises a chamber, a working fluid, an evaporation section and a condensing section. The chamber has an inner wall, and the working fluid is sealed in the chamber. The evaporation section and the condensing section are located at the inner wall. The first grooves are disposed on the inner wall and connected to the evaporation section and the condensing section. The working fluid is vaporized at the evaporation section when absorbing heat from the heat source and condenses to a liquid phase and releases the heat at the condensing section, and the first groove provides a capillary force to drive the working fluid from the condensing section back to the evaporation section.

This Non-provisional application claims priority under U.S.C.§ 119(a) on Patent Application No(s). 093124814 filed in Taiwan, Republic of China on Aug. 18, 2004, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The invention relates to a heat dissipation apparatus and a manufacturing method thereof, and in particular to a vapor chamber and a manufacturing method thereof.

With progress in technologies, the number of transistors per unit area in an electronic device has increased. To maintain an effective operating temperature, additional fans and dissipation fins are commonly deployed to expel heat to the exterior. Heat pipes, a popular choice providing heat dissipation from a heat source, for example, can efficiently transmit large amounts of heat long distances from a reduced section area and minimal temperature difference therebetween without requiring additional power electricity or much space.

A heat pipe typically comprises a vapor chamber, a wick structure and a working fluid. The working fluid in the chamber is vaporized at an evaporation section as latent heat is absorbed and then condenses to a liquid phase and releases the heat at a condensing section as latent heat is released. Then, the liquid working fluid at the condensing section can be driven back to the evaporation section by the capillary force of the wick structure. Conventionally, the wick structure can be classified into four parts: mesh wick structure, fiber wick structure, sinter wick structure and groove wick structure.

The groove wick structure is formed on an inner wall of the chamber by mechanical carving. However, under the limitations of movement of the mechanical jig, only spiral and straight grooves can be formed on the inner wall of the vapor chamber, so that the working fluid at the condensing section cannot be efficiently flowed back to the evaporation section along the limitedly arranged grooves of the wick structure. Furthermore, width of the spiral or straight groove can only achieve about 300 μm by the mechanical process, providing insufficient capillary force so that the flow rate of the working fluid is slow and the heat dissipation efficiency is greatly affected.

The sinter wick structure is formed by a packed powder sintered and shaped at a high temperature. Because the sinter wick structure has a wick structure smaller than that of the spiral or straight grooved wick structure, the heat dissipation efficiency of the sinter wick structure is better than that of the groove wick structure. However, the metallic chamber is usually softened after an annealing process, so that it is easily deformed or cracked under external force. Although the chamber can be thicken or enlarged, heat dissipation efficiency is correspondingly decreased and weight thereof increases. Thus, it is important to provide a heat dissipation apparatus to facilitate heat dissipation efficiency in the small-size, dense and integrated electronic devices or circuits.

SUMMARY

The invention provides a heat-dissipation apparatus with lightweight and good performance in heat dissipation. The heat-dissipation apparatus includes a chamber, a working fluid, an evaporation section and a condensing section. The working fluid is sealed in the chamber. The evaporation section and the condensing section are located at the inner wall of the chamber. The working fluid is vaporized at the evaporation section when absorbing heat from the heat source, and then condenses to a liquid phase and releases the heat at the condensing section. At least one first groove is on the inner wall and connected to the evaporation section and the condensing section and providing a capillary force to drive the working fluid from the condensing section back to the evaporation section.

In addition, at least one second groove is disposed on the inner wall and connected to the first groove. The chamber is formed by folding the base plate, and the second grooves are located at a folded region on the base plate. The second groove is relatively wider than the first groove.

Further, the invention provides a method for manufacturing the heat-dissipation apparatus. The method includes the steps of: providing a base plate; forming an evaporation section, a condensing section and at least one first groove on the base plate; and folding the base plate into a chamber so that the evaporation section, the condensing section and the first groove are disposed on an inner wall of the chamber.

The first grooves are formed on the base plate by a miniature molding process, and the miniature molding process includes steps of: providing a substrate; applying a pre-patterned layer on the substrate and forming the pre-patterned layer into a pre-patterned mold by a Micro Electro-Mechanical System (MEMS) process; providing a pattern material to the pre-patterned mold to form a patterned mold; and molding the base plate by the patterned mold, such that the evaporation section, the condensing section and the first grooves are formed on the base plate.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is a schematic view shows that a heat-dissipation apparatus according to a preferred embodiment of the invention is used to a heat source.

FIG. 2 is a sectional view of the vapor chamber in FIG. 1.

FIG. 3A is an exploded view of the vapor chamber in FIG. 2.

FIG. 3B is a schematic view shows the vapor chamber in FIG. 3A is formed by a folded base plate.

FIGS. 4A and 4B are two schematic views of another two base plates.

DETAILED DESCRIPTION

FIG. 1 is a schematic view shows that a heat-dissipation apparatus according to a preferred embodiment of the invention is used to a heat source. The heat-dissipation apparatus 10, such as a vapor chamber or a homoeothermic chamber, can be used to a heat source 12 such as a CPU, or an electrical component giving out heat. A metallic bottom plate 11, typically made of copper, is attached to the heat source 12, such that heat from the heat source 12 passes directly through the heat-dissipation apparatus 10 via the bottom plate 11, and then is quickly removed to the exterior.

Referring to FIG. 2, which is a sectional view of the vapor chamber in FIG. The heat-dissipation apparatus 10, preferred a vapor chamber, includes a working fluid, an evaporation section 21, a condensing section 22 and a wick structure 23 formed by at least one first miniature groove. The evaporation section 21, the condensing section 22 and the wick structure 23 are formed on the inner wall 24 of the vapor chamber 10. The working fluid is stored and circulated in the sealed chamber so as to dissipate heat from a heat source to the exterior. The working fluid is an inorganic compound, water, alcohol, liquid metal, ketone, refrigerant, or an organic compound.

The evaporation section 21 of the vapor chamber 10 is preferably disposed corresponding to the heat source 12, such that heat from the heat source 12 can be directly transmitted to the evaporation section 21 via the bottom plate 11. The working fluid at the evaporation section 21 is vaporized to a gaseous phase as the working fluid absorbs heat from the heat source 12, and the vaporized working fluid condenses to a liquid phase and releases the heat at the condensing section 22 as latent heat thereof is released. Then, the liquid working fluid is driven beck to the evaporation section 21 by a capillary force of the wick structure 23.

Referring both to FIGS. 3A and 3B, FIG. 3A is an exploded view of the vapor chamber in FIG. 2, and FIG. 3B is a schematic view shows the vapor chamber in FIG. 3A. The manufacturing method of the vapor chamber includes the steps as follow: Firstly, a base plate 25 is provided and the evaporation section 21, the condensing section 22 and the wick structure 23 are formed on the base plate 25. Then, by folding the base plate 25 and sealing two edges of the base plate 25 by welding or other methods achieve the construction of a pipe 26, as shown in FIG. 3B. When one end of the pipe 26 is sealed, the pipe 26 is filled with the working fluid. After the pipe 26 filled with the working fluid is evacuated by vacuum, the other end of the pipe 26 is sealed to form a closed vapor chamber, and the evaporation section 21, the condensing section 22 and the wick structure 23 are formed on the inner wall of the vapor chamber.

In the preferred embodiments, the evaporation section 21, the condensing section 22 and the wick structure 23 formed on the inner wall of the vapor chamber can be achieved either by molding the base plate with a mold or by a miniature molding process. The mode is made by a laser or a precision manufacturing technique. As for the miniature molding process, it preferably includes a mold manufacturing process and a molding process. The mold manufacturing process includes the steps of: providing a substrate; applying a pre-patterned layer on the substrate and forming the pre-patterned layer into a pre-patterned mold by a Micro Electro-Mechanical System (MEMS) process; providing a pattern material to the pre-patterned mold to form a patterned mold; and forming the patterned mold into a finished mold. The pattern on the finished mold (or on the patterned mold) is opposite the geometric structure formed on the base plate 25. Thus, by using the molding process and the finished mold (or on the patterned mold) to mold the base plate 25, the evaporation section 21, the condensing section 22 and wick structure 23 are formed on the base plate 25.

The wick structure 23 connects the evaporation section 21 and the condensing section 22, and provides a capillary force to drive the liquid working fluid at the condensing section 22 back to the evaporation section 21. It is noted that distribution of the wick structure 23 on the inner wall of the vapor chamber, i.e. the base plate 25, is not limited to the disclosed embodiment. In FIG. 3A, the wick structure 23 includes several straight first miniature grooves 231 a, 231 b and several second miniature grooves 232. Each second miniature groove 232 is connected with at lease two straight first miniature grooves 231 a or 231 b, such that the working fluid still can flow back to the evaporation section 21 along the straight first miniature grooves 231 b and 231 a even if some of them are blocked or malfunctioned. Furthermore, the second miniature groove 232 is relatively wider than the straight first miniature groove 231 a or 231 b. Therefore, the working fluid in the straight first miniature groove 231 b can be merged into the second miniature groove 232 and then flow back to the evaporation section 21, so that the flowing speed of the working fluid is improved.

Considering the construction of the vapor chamber formed by folding the base plate 25, it is preferable to build up the second miniature grooves 232 at a folded region of the base plate 25 to facilitate the following process of manufacturing the pipe 26.

Further, referring to FIGS. 4A and 4B, which are two schematic views of another two base plates. Because the wick structure of the present invention is formed by a laser, a precision manufacturing technique or a miniature molding process, such that the miniature groove can be achieved substantially 100 μm wide or less and thus the capillary force of the wick structure is greatly increased. Furthermore, distribution of the miniature grooves of the wick structure can varied corresponding to the need of the heat source. For example, the straight first miniature grooves 231 a are radially extended out from the evaporation section 21, as shown in FIG. 3A. Or, the first miniature grooves 231 and the second miniature grooves 232 are collocated to form a grid pattern on the base plate 25, as shown in FIG. 4A. Furthermore, as shown in FIG. 4B, several annular first miniature grooves 231 c are concentrically disposed and focusing on the evaporation section 21, and several straight first miniature grooves 231 a are radially extended out from the evaporation section 21 and intersectively and connected to the annular first miniature grooves 231 c. In addition, several second miniature grooves 232 with greater widths connect between the straight first miniature grooves 231 a and the annular first miniature grooves 231 c.

Therefore, the heat-dissipation apparatus of the invention presents a vapor chamber with lightweight and good performance in heat dissipation. The miniature grooves formed by laser, precision manufacturing technique or miniature molding process facilitate efficiency of heat dissipation, and an economical material of the vapor chamber decreases weight and cost thereof.

While the invention has been described with respect to preferred embodiment, it is to be understood that the invention is not limited thereto the disclosed embodiments, but, on the contrary, is intended to accommodate various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

1. A heat-dissipation apparatus for a heat source, comprising: a chamber comprising an inner wall; a working fluid sealed in the chamber; an evaporation section and a condensing section located at the inner wall; and at least one first groove disposed on the inner wall and connected to the evaporation section and the condensing section, wherein the working fluid is vaporized at the evaporation section when absorbing heat from the heat source and condenses to a liquid phase and releases the heat at the condensing section, and the first groove provides a capillary force to drive the working fluid from the condensing section back to the evaporation section.
 2. The heat-dissipation apparatus as claimed in claim 1 further comprising at least one second groove disposed on the inner wall and connected to the first groove.
 3. The heat-dissipation apparatus as claimed in claim 2, wherein the chamber is formed by folding a base plate, and each of the second grooves is located at a folded region of the base plate and is relatively wider than the first groove.
 4. The heat-dissipation apparatus as claimed in claim 2, wherein the first grooves are either radially extended out from the evaporation section or concentrically disposed and focusing on the evaporation section, or the first grooves and the second grooves form a grid pattern.
 5. The heat-dissipation apparatus as claimed in claim 2, wherein the evaporation section, the condensing section, the first grooves and the second grooves are formed on the inner wall of the chamber by a miniature molding process and the miniature molding process includes steps of: providing a substrate; applying a pre-patterned layer on the substrate and forming the pre-patterned layer into a pre-patterned mold by a Micro Electro-Mechanical System (MEMS) process; providing a pattern material to the pre-patterned mold to form a patterned mold; and molding the base plate by the patterned mold, such that the evaporation section, the condensing section, the first grooves, and the second grooves are formed on the base plate.
 6. The heat-dissipation apparatus as claimed in claim 2, wherein the evaporation section, the condensing section, the first grooves and the second grooves are formed on the inner wall of the chamber through a mold formed by a laser or a precision manufacturing technique.
 7. The heat-dissipation apparatus as claimed in claim 1, wherein the first grooves are either radially extended out from the evaporation section or concentrically disposed and focusing on the evaporation section, or the first grooves and the second grooves form a grid pattern.
 8. The heat-dissipation apparatus as claimed in claim 1, wherein the chamber is formed by folding a base plate, and the evaporation section, the condensing section and the first grooves are formed on the base plate by a miniature molding process.
 9. The heat-dissipation apparatus as claimed in claim 8, wherein the miniature molding process comprises steps of: providing a substrate; applying a pre-patterned layer on the substrate and forming the pre-patterned layer into a pre-patterned mold by a Micro Electro-Mechanical System (MEMS) process; providing a pattern material to the pre-patterned mold to form a patterned mold; and molding the base plate by the patterned mold, such that the evaporation section, the condensing section and the first grooves are formed on the base plate.
 10. The heat-dissipation apparatus as claimed in claim 1, wherein the evaporation section, the condensing section and the first grooves are formed on the inner wall of the chamber through a mold formed by a laser or a precision manufacturing technique.
 11. A method for forming the heat-dissipation apparatus, comprising steps of: providing a base plate; forming an evaporation section, a condensing section and at least one first groove on the base plate; and folding the base plate into a chamber so that the evaporation section, the condensing section and the first groove are disposed on an inner wall of the chamber.
 12. The method for forming the heat-dissipation apparatus as claimed in claim 11 further comprising a step of forming at least one second groove disposed on the inner wall and connected to the first groove.
 13. The method for forming the heat-dissipation apparatus as claimed in claim 12, wherein the chamber is formed by folding the base plate, and each of the second grooves is located at a folded region of the base plate and is relatively wider than the first groove.
 14. The method for forming the heat-dissipation apparatus as claimed in claim 12, wherein the first grooves are either radially extended out from the evaporation section or concentrically disposed and focusing on the evaporation section, or the first grooves and the second grooves form a grid pattern.
 15. The method for forming the heat-dissipation apparatus as claimed in claim 12, wherein the evaporation section, the condensing section, the first grooves and the second grooves are formed on the base plate by a miniature molding process, and the miniature molding process includes steps of: providing a substrate; applying a pre-patterned layer on the substrate and forming the pre-patterned layer into a pre-patterned mold by a Micro Electro-Mechanical System (MEMS) process; providing a pattern material to the pre-patterned mold to form a patterned mold; and molding the base plate by the patterned mold, such that the evaporation section, the condensing section, the first grooves and the second grooves are formed on the base plate.
 16. The method for forming the heat-dissipation apparatus as claimed in claim 12, wherein the evaporation section, the condensing section, the first grooves and the second grooves are formed on the base plate through a mold formed by a laser or a precision manufacturing technique.
 17. The method for forming the heat-dissipation apparatus as claimed in claim 11, wherein the first grooves are either radially extended out from the evaporation section or concentrically disposed and focusing on the evaporation section, or the first grooves and the second grooves form a grid pattern.
 18. The method for forming the heat-dissipation apparatus as claimed in claim 11, wherein the evaporation section, the condensing section and the first grooves are formed on the base plate by a miniature molding process, and the miniature molding process includes steps of: providing a substrate; applying a pre-patterned layer on the substrate and forming the pre-patterned layer into a pre-patterned mold by a Micro Electro-Mechanical System (MEMS) process; providing a pattern material to the pre-patterned mold to form a patterned mold; and molding the base plate by the patterned mold, such that the evaporation section, the condensing section and the first grooves are formed on the base plate.
 19. The method for forming the heat-dissipation apparatus as claimed in claim 11, wherein the evaporation section, the condensing section, the first grooves and the second grooves are formed on the base plate through a mold formed by a laser or a precision manufacturing technique.
 20. The method for forming the heat-dissipation apparatus as claimed in claim 11, wherein the step of folding the base plate into a chamber further comprises steps of: folding the base plate to form a pipe; sealing one end of the pipe; filling a working fluid into the pipe and vacuuming; and sealing the other end of the pipe. 